5 Boro Bike Tour Tandem Trike: The Wheel Deal

The Viking Tandem Trike plans call for a 20″ BMX rear wheel with 48 spokes for added strength. Since I’m building everything from scratch, I thought I’d go one better.

As it turns out, a 16″ motorcycle/moped wheel is the same diameter as a standard 20″ BMX bicycle wheel. As a result, I won’t have to change the geometry of the frame. Pretty cool, huh?

The wheel is made of a cast aluminum and magnesium alloy, so it’s extremely strong. It is stronger than a standard bicycle wheel and I’ll never have to worry about it going out of true. For a tandem this is very important because with weight of 2 adults on the trike and their combined pedaling power, the last thing I want to worry about is if the rear wheel is up to the task.

I want to use a fat tire on the back and the moped wheel is perfect for this. The photo shows a 2.25″ wide tire mounted. There are wide BMX rims available but they can be expensive. Chopper Bikes and Fat Bikes are trendy now so rims that safely accomodate a 3″ or larger tire are sold at a premium price. Finding a rim with 48 holes that fits the task and budget is difficult. This moped wheel will easily accomodate a 3 inch wide tire. I could even go larger, but I think that will be enough. Besides, you can see from what I paid that I couldn’t have gotten better bargain.

Since there is no suspension on the trike, a fat rear tire will allow some cushioning of the bumps. The larger contact patch of the fat tire will make for better traction too.

The moped wheel has a bonus feature – an integrated drum brake. Designed to stop a motorized vehicle, it will surely be able to stop a fully laden trike. Of course, I’ll have disc brakes on the front wheels, so it won’t need to be the only brake, but it’s a nice feature. It will also be used as a parking brake.

Even with the drum brake and cast alloy construction, the wheel isn’t very heavy. I compared it to a 26″ mountain bike wheel with a Shimano Nexus 7 internal geared hub I have and the weight is about the same. Anyway, I’m not building a racing bike here. Counting grams on a tandem trike is just silly.

The steel tubes for the main frame have been ordered and will arrive mid-February. I’m still confident we’ll make the May deadline. Stay tuned.